Asthma is a common chronic inflammatory disease of the airways, which affects approximately 26 million people in 2010 and costs $56 billion each year in the US. In particular, 7 million children suffer from asthma (~9.5%) which causes more than 14 million lost school days due to asthma exacerbations. Although triggers to pediatric asthma exacerbations are well recognized such as infections, allergy, smoke, chemicals, and exercises, how the interactions among the environmental factors and the patients' biological and behavioral characteristics determine the susceptibility to and timing of such events is less clear. One significant barrier to the causal understanding is the lack of objective measures on exposure metrics correlated with patient physiological responses and activities. Therefore, there is a significant unmet need to develop integrated sensor monitoring systems that can be deployed in a child's daily life and collect real-life environmental, physiological and behavioral data for epidemiological studies of asthma. This work proposes to capitalize on the recent technological advancements in wearable sensors and microfluidic point-of-care diagnostics, and the ubiquitous smartphone platforms to develop novel ambulatory integrated sensor systems for collecting such real-life data, which will enable the rigorous testing of hypotheses on environmental contributions to the causation of asthma exacerbations. Specifically, we will utilize flexible electronics, handheld microfluidics and commercially available gas, flow and activity sensors to build a wristband monitoring environmental air pollution and patient activities a handheld immunosensor for saliva total IgE and inflammatory marker cytokine IL-13 tests, and a smartphone attachable spirometer. Three specific aims are proposed to achieve the sensor developments, integration with informatics platforms and validation with pilot studies on pediatric asthma patients. Specific Aim 1. Is to design and implement three ambulatory sensors: a wristband capable of monitoring air pollutions and patient activities, a handheld microfluidic immunosensor for total IgE and cytokine tests, and a smartphone attached spirometer for lung function measurements. Specific Aim 2. Is to integrate the ambulatory sensor array with smartphone based informatics platform that will developed by the companion PRISMS FOA RFA-EB-15-003. Specific Aim 3. Is to validate the ambulatory sensor arrays in a pilot clinical study with inner-city pediatric asthma patients.